Texas Walnut grows in the following 7 states and provinces:

Information about Texas Walnut:

The Juglans Microcarpa is commonly known as the Dwarf Walnut, Little Walnut, Mexican Walnut, Namboca, Nogal, Nogalillo, Nogalito, River Walnut, Texas Black Walnut, Texas Walnut as well as Walnut.

The currently accepted scientific name of little walnut is Juglans
microcarpa Berl. . Two varieties are delineated on the basis of
morphological differences such as leaf and fruit size . The
following varieties are commonly recognized :
Juglans microcarpa var. microcarpa
Juglans microcarpa var. stewartii
Little walnut hybridizes with the closely related Arizona black walnut
(Juglans major) , and populations which exhibit various intermediate
characteristics have been reported . At the eastern edge of its
range, little walnut intergrades with black walnut (J. nigra) .

Little walnut grows from southwestern Kansas through Oklahoma to central
New Mexico and Texas, south into northeastern Mexico . In
Texas, little walnut grows from the valley of the Colorado River west to
the mountains of the Trans-Pecos . The variety stewartii grows in
the Chisos Mountains of Texas and extends into Mexico .